Transport Layer Security Protocol (TLS or TLSP) and its predecessor, Secure Sockets Layer (SSL), are cryptographic protocols that provide secure communications on the Internet for such things as web browsing, e-mail, Internet faxing, instant messaging and other data transfers. It operates at the transport layer of the OSI model by placing data into routeable packets with encrypted payloads in a manner that is invisible to the user of the application. There are slight differences between SSL and TLS, but they are essentially the same.